The tragic drama teaches us that the spheres of logic, order, and justice are terrifyingly finite and that no progress in our science or our technical means can move their limited boundaries. Outside and inside the human being, there is the "other" of the world. Give it whatever name you like: invisible or malevolent god, blind fate, mandates of hell, or the raw fury of our bestial blood. This "other" sets up a trap for us at the crossroads. It mocks us and destroys us. In some rare cases, after the destruction, it leads us to an incomprehensible redemption.
I know that none of these things is a definition of tragedy. However, a definition of tragedy would not be a definition either, but rather an abstract determination. When we say "tragic drama" we roughly know what we are talking about. Not exactly, of course, but the phrase "tragic drama" is enough to make us understand what we are dealing with.